github.com/cockroachdb/cockroach@v20.2.0-alpha.1+incompatible/pkg/geo/geogfn/dwithin.go (about)

     1  // Copyright 2020 The Cockroach Authors.
     2  //
     3  // Use of this software is governed by the Business Source License
     4  // included in the file licenses/BSL.txt.
     5  //
     6  // As of the Change Date specified in that file, in accordance with
     7  // the Business Source License, use of this software will be governed
     8  // by the Apache License, Version 2.0, included in the file
     9  // licenses/APL.txt.
    10  
    11  package geogfn
    12  
    13  import (
    14  	"github.com/cockroachdb/cockroach/pkg/geo"
    15  	"github.com/cockroachdb/cockroach/pkg/geo/geographiclib"
    16  	"github.com/cockroachdb/errors"
    17  )
    18  
    19  // DWithin returns whether a is within distance d of b, i.e. Distance(a, b) <= d.
    20  // If A or B contains empty Geography objects, this will return false.
    21  func DWithin(
    22  	a *geo.Geography, b *geo.Geography, distance float64, useSphereOrSpheroid UseSphereOrSpheroid,
    23  ) (bool, error) {
    24  	if a.SRID() != b.SRID() {
    25  		return false, geo.NewMismatchingSRIDsError(a, b)
    26  	}
    27  	if distance < 0 {
    28  		return false, errors.Newf("dwithin distance cannot be less than zero")
    29  	}
    30  
    31  	aRegions, err := a.AsS2(geo.EmptyBehaviorError)
    32  	if err != nil {
    33  		if geo.IsEmptyGeometryError(err) {
    34  			return false, nil
    35  		}
    36  		return false, err
    37  	}
    38  	bRegions, err := b.AsS2(geo.EmptyBehaviorError)
    39  	if err != nil {
    40  		if geo.IsEmptyGeometryError(err) {
    41  			return false, nil
    42  		}
    43  		return false, err
    44  	}
    45  	spheroid := geographiclib.WGS84Spheroid
    46  	maybeClosestDistance, err := distanceGeographyRegions(spheroid, useSphereOrSpheroid, aRegions, bRegions, distance)
    47  	if err != nil {
    48  		return false, err
    49  	}
    50  	return maybeClosestDistance <= distance, nil
    51  }